Method of producing antifriction bushings



Oct. l5, 1929. ego, FnnrNE'v y METHOD AoF PBQDUcI-NGANTIFRICVTIONBUSHINGS Filed mp1s, 1927- Patented Oct. 15, l1929 CLARENCE Q. PAYNE, OFNEW YORK, N. Y.

METHOD OF PRODUCING ANTIFBICTION BUSHINGS Application led February 16,1927. Serial No` 168,612.

This invention relates to improvements in antifriction bushings ofbearings which support rotating, oscillating or 'reciprocating members,and it comprises improved means for efficiently embodying the inventiondescribed in Letters Patent No. 1,600,961 granted to me for means forreducing the sliding friction of contact members. n In accordance withthe above invention, by making both of two contact surfaces of a ibearinor of much harder metal than has here tofore been consideredfeasible and by giving at least one of them a plastic or resilientsupport, a very low coeilicientof sliding friction is obtained. Whileboth of the surfaces should be of substantially the same order ofhardness, as for example chromium and case hardened steel, the hardnessof the latter being slightly variable, may be made somewhat less thanthat of the former for economy of replacement. My present invention isconcerned with the member having a chromium contact surface, and with ameans and method for making it efficiently and economically availablefor antifriction bushings.

The invention consists essentially in using a wrought or rolled metalbushing, one of whose surfaces is polished and electroplated, while dat,with a layer of hard metal Whose thickness and surface is controlled byconditions of the electrolytic deposition, and which is finally shapedby pressure to a cylindrical o'r other form desired.

In the accompanying drawings which show a preferred method of practicingthe invcntion,

Figure 1 illustrates the shaping of theI flat steel metal plate intocylindrical form by bending it with the plated surface on the inner orconcave side.

Figure 2 shows a perspective view of the bushing of Figure 1.

Figures 3 and 4. illustrate means for keeping the bushing from rotatingin its support by means of a key or a flanged edge of the sheet lmetalbushing.

Figure 5 illustrates in outline or diagrammatically, the electrolyticdeposition of the chromium plating on a flat sheet metal plate or anode.

It has been the general practice heretofore to make the bushing of abearing which supports the shaft of power transmitting machinery of amuch softer metal, such as babbitt or bronze, etc., than that of itsjournal or shaft which is usually made of steel. The object is to causethe wear of the sliding surfaces to be taken by the bushing and thusprotect the more expensive shaft from Wear,

in order to reduce the cost of re airs and renewals. This practice ofmaklng the contact metals of a bearing of a wide difference in hardness,such as steel and bronze, etc., does not, however, secure a lowcoefficient of sliding friction, especially where the surc5 faces moveat high speeds and under relatively heavy pressures. My invention setforth in Patent No. 1,600,691 departs radically from this generalpractice. It employs metals of a high order of hardness such aschromium, which is one of the hardest known metals, for at least one ofthe contact surfaces. This is ,given a resilient or plastic sup ort inorder to distribute the pressure uni ormly over the supporting surfaces,and

in this way a very low coefficient of sliding friction of the contactsurfaces is obtained. In a certain case my present invention reversesthe usual practice by making the bushing the more durable of the twocontact mem'- so bers. v

In. constructing thev bushing of a bearing y to carry out my inventionrIpreferably employ a thin sheet of rolled metal 1 in order to obtain acertain degree of flexibility or `a5 resilience in shaping it to itsfinal form, as, ,Y

well as for subsequent adjustment -topressure. This metal may be eithersoft'iron, brass, copper, aluminum, etc., but is preferably of bronze.It is cut to the dimensions required by the length and diameter of itsbearing, and flattened. Shallow grooves 2 are then formed on one surfacefor graphite or oil lubrication so that the pressure supporting areasshall frequenty alternate with areas which provide means forlubrication.l These grooves may be placed either parallel with the axisof the bearing, or at an angle to it as shown in Figure 2. The frroovedsurface of the bushing blank is buffd or burnished l` ceive a highpolish before it is plated for two reasons-one is that any filmof oxide,always more 0r less present on metal which has been subjected to heatand pressure, is thereby removed. This secures for the chromium lating amore intimate contact and firmer ond with the metal backing than is thecase with a tarnished' surface. The other reason is that chromiumplatinghaving a' 4 polished or mirror surface gives a lower coefficient ofsliding frictiony than one having a dull or roughened surface. Thismirror surface of chromium'becomes an exact reproduction of the polishedsurface of its backing metal when the conditions of the electrolyticbath, as regards temperature., current density and acidity are profperlyad]u`sted in order to secure this type o surface in place of a satinfinish, or one having a still rougher surface.

Any subsequent machining or polishing is thus avoided, which would bediflicultand expensive with so hard a metal as chromium. This mirrorsurface is therefore on essential element of my present invention.

As illustratedthe chromiui anodes 12 are immersed in the electrolyte 11and the sheets 1 comprising the cathodes plated in the conventionalmanner.

An important advantage in plating a flat metal sheet with chromium isthat a more uniform thickness of metal can thus be obtained. Chromiumdoes not throw well in electroplating, i. e., it does not cover hollowsor deep v recesses with a uniform thickness of metal.

If cast metal bushings are therefore split and plated with chromium thethickness of the plating will varysomewhat around the innercircumference of the bearin surface. Such' bushings give an imperfectcaring support. In carrying out the plating operation two of the groovedand polished sheet metal blanks may conveniently be placed back to backin the electrolyte tank as indicated at 1-1 in Fi re 5 in order to plateonly one surface eac of the two blanks. They thus form the cathodeswhile-the anodes 12-12 placed respectively opposite them are made ofsuch surface areas with respect to the areas of the cathode blanks as t0insure a uniform thickness of chromium lating along the entire exposedareas. In t is way a better -control of the chromium plating is obtainedand any slight variation brought within the fit or tolerances requiredof accurate machine Work.

*This is attained without any subse uent machining or grinding whatever.T e actual thickness of the chromium plating may vary with the nature ofthe service for which the bushing is designed,but usually it will notexceed .001 to .002.

The final operation consists in shaping the flat chromium plated blank 1by ressure to enable it to assume a cylindrical f) dicated in Figures 1and 2, with thechromium lating on the inner or concave side. This s a.ing may be done b mechanical means as y rolling or by a hy raulic punchand die as may befound most convenient. Not oiily is the flexibility ofthe bushing increased b the ooving of its inner surface ybut ,the e geso the grooves being thus made to approach slightly, they liold firmlyany solid lubricant like graphite, inserted in them. When utilized for ashaft bushing and placed in its bearing support the bushing may be heldfrom rotating by tinning the inner bearing surface 'and then sweating inthe bushingwith hot solder, or a key 3 fitting between the edges of thebushin and into a key way 4 iii the bearing 5 may ge employed in placeof solder as shown in Fi ure 4,-or one end 6 of the bushing may eslightly flanged-as shown in Figure 3. In the latter case a narrow slot7 is cut in the bearing,- and the flange is then inserted in it when thebushing is Forced into its bearing seat. If desired the sheets 1 may beof large size and after plating may be cut into smaller pieces forfoiniin a plurality of bearings with the one plating operation.-

An antifriction bushing made in accordance with my present inventionsecures many important advantages. A chromium plated surface having ahigh polish may thus be made to conform to the accuracy of a machine fitwithout any machine work extended upon it. The coeiiicient of slidingfriction, by reason of the hardness and smoothness of the contactsurface is also greatly reduced, especially when employed in cooperationwith a pressure bearing surface having substantially the same order ofhardness as described in my Patent No. 1,600,961. The sheet metalbacking employed is sufficiently soft metal to enable it to be shaped bypressure and having a series of lubricating grooves ormed in itpreferably by roll pressure while flat,-the chromium plated areas arethus given a plastic or resilient support for its oooperating ressuremember. In this way a highly e cient antrifriction bushing can be madewith practically no machine work. Its weight so constructed will notexceed about one uarter that of the usual cast or drawn bronze usliingfor shaft bearings.

While I have referred to my invention in connection with a bushing forshaft bearings, it will be readily understood that it can likewise beutilized with equal advantage for linings-having reciprocating pressuremeinbers as well, such as steam engines, air comorm as inf pressors,refrigerating machines, and automobile engines, etc. In such cases thelubricating grooves may preferably be filled with a soft metal likebabbitt, solder, etc. in place of graphite to insure a tight :tit undersevere service and to prevent possible leakage of gas 'between thepiston rings and the cylinder Wall lining.

llt will be understood that the invention is not limited to the detailschosen to illustrate the same, but that various modifications andchanges may be made therein Without departing Jfrom the spirit of theinvention or the scope of the appended claims.

Having thus described my invention vI claim:

l. The method of producing an antifriction bearing, Which comprisesproviding a flat sheet of relatively plastic Wrought metal of a lowdegree of hardness, electroplating the same While in a fiat conditionwith an antifriction material of a high degree of hardness and bendingthe plated sheet into 'a bearing With the plated surface exposed to Wearand the material of a lov:r degree of hardness forming a cushioning backfor the Wearing surface.

2. The method of producing an antifriction bearing, Which comprisesproviding a flat sheet of relatively plastic Wrought metal,electroplating the same While in a. Hat condition with chromium andbending the plated sheet into a bearing with the chromium surfaceexposed to the moving part-s and the relatively plastic material forminga cushioning hack for the vvearino` surface.

3. The method o? producing an antifric-` tion bushing, which comprisesproviding a fiat sheet of relatively plastic wrought metal, depositing asmooth layer of chromium thereon While in a fiat condition and shapingsaid sheet into a bushing with the chromium surface exposed to themoving parts and the relatively plastic material orming a cushioning rback for the Wearing surface.

In testimony whereof I have aixed my sig nature to this specification.

CLARENCE Q. PAYNE.

